Recently, the spread of broadband services makes viewing of video contents through a network easier, and it is anticipated that more than half of the data on a network will be video data in near future. In such circumstances, video encoding is employed so as to effectively utilize the network bandwidth. At present, a video encoding system such as MPEG2 or H.264/AVC is utilized.
In order to further improve the encoding efficiency, standardization of HEVC has been promoted. The HEVC employs units such as CU (Coding Unit), PU (Prediction Unit), and TU (Transform Unit) for individual processes, and the size and mode of each unit is determined so as to obtain an optimum RD (Rate Distortion) cost, which can improve the encoding efficiency twice as much as that obtained by H.264 (see, for example, Non-Patent Document 1).